A filter of this kind is described, e.g., in SE-C-8305817-2 and corresponding EP-B1-0160069 and U.S. Pat. No. 4,634,529, respectively. According to this patent, the backwash barriers, i.e., barriers preventing re-wetting of a filter cake, such as dehydrated fibers, deposited on the filter elements, extend from each filter element into associated axially directed conduits and comprise an extension of the trailing edge of the filter element as seen in the direction of rotation. It has been found that backwash barriers arranged in this way are relatively complicated to accomplish in practice.